Spend profiles and resource histograms
Spend profiles and resource histograms are simple to create once costs are added to labour, equipment and materials used in the march chart. Figure 9 illustrates an example where the weekly cost per crew and the total cumulative cost is presented in a histogram and table. It is also possible to display the resource histogram per week (or month or day) to determine camp requirements. Spend profiles are a function of time and are displayed parallel to the time axis of the march chart. It is also possible to create a spend profile parallel to the distance axis to show the cost per section of the pipeline. Any changes to the march chart (i.e. crew moves) would automatically create a change to the spend profile.
Applying work and speed profiles to crews
Most estimates, schedules and march charts assume a consistent productivity (or work) rate for each pipeline crew along the ROW. This productivity factor is then applied for the entire length of the spread to determine the duration of each crew. Applying a constant productivity rate for a crew doesn’t account for changes in profile, soil, terrain (muskeg versus mineral soil conditions) or vegetation type.
For example, a logging crew that has a productivity rate of 2000 m/day would require 15 days to complete a 30 km ROW. While this provides a rough estimate it doesn’t account for productivity rates based on changes in vegetation types or whether there is any logging required in certain areas (for example an old burn area that doesn’t have any salvageable timber).
The following examples (Figure 10 and Figure 11) illustrate the difference when a vegetation classification system is used to define the productivity rates for a logging and clearing crew in a Northern pipeline spread. In this example the vegetation data and productivity rates for both crews in a particular location were imported directly into the march chart from an Excel data file supplied by a survey.
In Figure 10 we can see that the logging and clearing crews have very similar productivity rates and a duration of 25 and 26 days respectively for the logging and clearing crews.
The vegetation index in this example defines the amount of work (area in ha) and work rate for each vegetation type along the ROW. Once this data is known and available in a spreadsheet format, it is easy to apply this index to each crew as shown in Figure 11 below. The first noticeable change is that the crews are not consistently progressing along the ROW. Each crew line now reflects a different productivity rate with each change in vegetation type. More importantly we can see that the duration for each crew has changed significantly. Logging has decreased from 25 days to 16 days while the duration for Clearing has increased from 26 days to 40 days!
This approach could easily be used in any other geographic location where a known variable impacts the work rate of crews along a ROW. The ability to define productivity in terms of the ROW conditions will enable you to create a more accurate project plan and spend profile when compared to simply applying a uniform rate to each crew.
Applying a speed profile to a crew, based on known changes in productivity, creates a more accurate picture of how the crew is moving along the pipeline ROW (Figure 12).
Progressing March Charts
Progressing crews on a march chart requires the start KP, end KP and the date range for each progress period (based on the inspector field reports) is applied. The exception to linear meters would be counting the number of welds (usually back end welds) or the number of UPI items (such as bag weights).
Figure 13 (below) shows progress for both the grade and the haul & string crews. Progressing is as simple as selecting a crew by clicking on it, right click and select enter progress. Enter the start
and end date for the progress period and the start and end KP. The march chart software calculates the physical percent complete based on the amount of work completed divided by the total length of the pipeline. In this example grading is 61.02% and haul & stringing is 40.44% complete. It should be noted that this progress is for the segment that starts at KP 0+000 and ends at restricted access area, it doesn’t include the other two segments for each of these crews.
Progress Bar Charts
Progress can also be indicated in a bar chart format where each the progress of each crew is represented by a shaded bar chart. As progress is applied to a crew the bar chart view is automatically updated to reflect this progress. In Figure 14 the direction of build is from right (KP 162+000) to the left (KP112+000). In this example the clearing, pioneering and grade crews have completed the entire length of the spread. Haul & String are between 40% and 50% complete. The automatic welding crew has just started.
The goal of this guide was to provide a comparison of traditional scheduling tools to march charts which are better suited for linear construction projects such as a pipeline. This overview of march charts went from explaining and drawing simple lines on the march chart, to adding constructability issues (environmental restrictions) and risk (weather). Other risks can just as easily be added to the march chart to develop a clearer picture of the pipeline job. Creating spend profiles is simply a matter of applying costs to each crew.
As described, it is fairly easy to apply speed and work profiles to crews to connect the productivity rates to soil, timber or any other factor that will have an impact. Progressing during project execution is dependent on the addition of crew inspector report data. Typically the start and end KP for each crew is recorded daily. UPI items and welding may be tracked as the number installed or completed each day.
March charts connect the schedule to the geography and risks of a project in a manner that is not at all possible using non-linear methods. Hopefully this guide has helped you understand the basics of march charts and the opportunities that are possible.